Symmetric-Key Encryption

Encryption that uses the same key for both encryption and decryption.

Block Cipher
Encrypts data in single “chunks.” e.g. 128-bit chunks
  • Data Encryption Standard (DES) Uses 64-bit block and 56-bit key
    • Susceptible to brute force attacks
      • Attempted secure derivatives:
        • 3DES, International Data Encryption Algorithm (IDEA), and Blowfish
Stream Cipher
Encrypts data on-the-fly a single bit at a time.
  • Revest Cipher 4 (RC4)

    • Stream cipher
    • 2001-2013 weaknesses discovered in RC4
    • Considered insecure and a legacy cipher
  • Advanced Encryption Standard (AES)

    • Block cipher
      • Uses 128-bit block size and 128-, 192-, or 256-bit key size
    • Very secure and practically uncrackable
    • Very fast
    • Not just limited to TCP/IP apps, also TLS
      • Many TCP/IP apps still moving towards adoption
  • Extended markdown support in VimWiki, for example, definitions